The present invention relates to current drivers and particularly to current drivers suitable as display drivers for organic EL (electro luminescence) panels, LED (light emitting diode) panels and the like.
In recent years, flat panel displays have their screen sizes and definitions increased while having their thicknesses, weights and production costs reduced. In this situation, display drivers have been required to enhance uniformity in display quality by reducing variation in output currents between output terminals. Current variation occurring during static operation of a current mirror is due to variation occurring in diffusion processes for individual transistors and variation in gate voltage caused by resistances of power lines, for example. Current variation occurring during dynamic operation of a current mirror is due to injection of charge from a display panel or instantaneous variation of power, for example. A driver semiconductor generally has a multiple-output configuration and is in the shape of a slender rod in order to be mounted in a frame portion of a flat panel. Because of this constraint on the LSI shape, characteristics of output transistors arranged on the driver semiconductor differ from one another depending on their positions on the slender layout of the driver semiconductor. Accordingly, even when the same gate voltage is applied to the output transistors, output currents from respective current mode D/A converters are not always the same.